1. Field of the Invention;
The present invention relates to a system for securing an illumination or lighting instrument to the ceiling of a room by suspending the same from a slab of a building structure.
2. Prior Art Statement:
In order to fixedly securing illumination instruments in a building used for office rooms and other purposes, there has hitherfore been used a system wherein illumination instruments are suspended from slabs of the building while using bolts and nuts for fixing the illumination instruments at desired height. In this known system, a straight bolt is cut to have a length measured to extend from the surface of a ceiling finish board to the slab, applied with rustproof treatment and then secured to the slab. A guide assembly having a chain for raising the illumination instrument is then attached to the bolt, followed by adjustment of the height, and then an illumination support plate or housing is raised by the chain. After detaching the guide assembly, a nut and a washer are fitted on the bolt and then the nut is threaded so that it moves upwards to fix the illumination instrument.
However, this known system has disadvantages that cumbersome and dangerous operation is necessary for fixing the illumintion instrument resulting in reduction in operation efficiency, since the relatively heavy illumination instrument must be supported by least two workers' hands who are staying on high stepladders and the illumination instrument must be raised and lowered by them to adjust the height of the illumination instrument so that it is snugly fitted to cover an opening of the ceiling finish board. The known system has a further problem that an additional anchor must be driven into the slab at a different position when the existing anchor for suspending the bolt from the slab is not exactly coplanar with the opening of the ceiling finish board.